Platelet rich plasma or PRP is a biological product that initiates healing responses in tissues throughout the body. Platelets circulate throughout our blood to facilitate clotting and wound closure by releasing bio-active proteins known as platelet growth factors.¹
How is PRP Processed?
Blood clotting and wound healing are the primary functions of platelets. Platelet concentration in a healthy individual varies between 150,000 to 450,000 platelets per microliter of whole blood.² Platelet rich plasma is a supraphysiologic concentration of platelets achieved by centrifuging whole blood. While there is not a standard protocol for PRP preparation, the process includes a blood draw between 10-120 ml followed by differential centrifugation. Blood is collected into tubes containing an anticoagulant such as sodium citrate to prevent the activation of platelets prior to injection. Initial centrifugation separates red blood cells from the ‘buffy coat’, a mixture of white blood cells and the platelet rich plasma. The platelet rich plasma and the upper layer of the ‘buffy coat’ are then transferred to a sterile tube for a second spin to isolate the PRP from platelet poor plasma. Specialized PRP kits facilitate the process, allowing physicians to administer PRP with platelet concentrations 6-7 times what is found in whole blood.
Orthopedic Applications of PRP
There is little risk associated with the use of platelet rich plasma injections. Clinical applications in the orthopedic space have been shown to be safe time and again. Allergic and immune responses are unheard of because PRP’s autologous nature.³ Orthopedic applications include tendon degradation or tendinopathies throughout the body; achilles tendinopathy, lateral and medial epicondylitis, rotator cuff injuries, and gluteal tendinopathy to name a few. PRP has also been shown to support cartilage repair in patients with osteoarthritis of the knees and hips, carpal tunnel syndrome and osteochondral lesions of the talus. When surgery is the best option PRP can improve outcomes for rotator cuff tears and spinal fusions.
Level IV evidence is available to support several orthopedic applications of PRP with published case series and case controlled studies. Though blinded, placebo controlled studies for each specific musculoskeletal condition will need to be completed in the future, the potential gains with PRP outweigh the risks when compared to oral medications, physical therapy and corticosteroid injections.
Aesthetic Applications of PRP
There is a huge demand to resolve cosmetic issues such as hair loss and scarring from acne, trauma or surgery. Though seemingly superficial, cosmetic concerns are known to have an enormous psychological impact; psychological health is intimately linked to physical health. PRP has emerged as a safe and effective treatment option to boost the body’s capacity to regrow hair and regenerate collagen in damaged epithelial tissues. PRP can reduce the appearance of acne scars, burns, surgical incisions and stretch marks by initiating cell proliferation and migration.
PRP Injections and Alternative Delivery Methods
PRP should be carefully injected directly at the site of injury for growth factors to be most effective. The use of fluoroscopy, real time X-ray imaging, improves outcomes for orthopedic surgeons by guiding injections to offer maximum benefit. PRP, when injected directly into damaged cartilage, tendons, ligaments or muscle, initiates a healing cascade by stimulating the local cells. Orthopedic application of PRP at the site of a bone graft or surgical incision has been shown to speed the recovery process and increase tissue adhesion. Cosmetic procedures yield results via intradermal injections or topical administration after microneedling or ablative laser treatment.
How does PRP Work Biologically?
Platelets are produced in the bone marrow by megakaryocytes. They are non-nucleated fragments of cytoplasm which contain more than 30 bioactive proteins.⁴ Platelets release cytokines, molecules which facilitate cell communication locally and throughout the body.⁵ Cytokines notify other cells if there is an injury, signalling nearby and distant cells to send reinforcements. Platelets also release alpha granules which contain platelet derived growth factor (PDGF). PDGF is a powerful chemo attractant that attracts other cells to the area where the granules are secreted.⁶ This causes cells to migrate and proliferate, dividing to form new tissues.
PDGF is involved in all three levels of wound healing; angiogenesis, fibrous tissue formation and epithelial cell accumulation (fibroblasts for internal wounds and collagen one for skin tissues). The concentrated dose of platelets to an area to promotes healing through the release of additional growth factors: transforming growth factor (TGF), platelet factor interleukin (IL), platelet-derived angiogenesis factor (PDAF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), insulin-like growth factor IGF and fibronectin.⁷
Preparing for a PRP Procedure
According to Stanford School of Medicine, patients should prepare for PRP procedures by hydrating and by discontinuing the use of nonsteroidal anti inflammatories (NSAIDs) for at least 7 days before the procedure. NSAIDs, such as ibuprofen, naproxyn, and indomethacin, work by blocking the action of some of the growth factors in PRP and will decrease the efficacy of a PRP injection.⁸ Therapeutic outcomes of the procedure generally take 6-8 weeks to adequately assess.
Future Impact of Platelet Rich Plasma Injections
Doctors across disciplines are just starting to tap into the regenerative potential of platelet rich plasma. There are few contraindications and because the procedure utilizes the patient’s own blood, side effects are rare and fleeting. PRP can help prevent surgery in some cases and when surgery is the only option PRP improves outcomes and speeds recovery. By maximizing the regenerative potential of damaged tissues, platelet rich plasma injections have created lasting change for countless patients, but because these injections are not generally covered by insurance, PRP has yet to become standard care. Insurance providers may begin to reimburse for this procedure once more Level I evidence is published.
Standard preparation and treatment regimes are another industry concern. According to a third party study, some commercially available kits aren’t delivering an adequate concentration of platelets to initiate healing responses. Additionally, the field of regenerative medicine will benefit from future studies evaluating the ideal concentration, dosage and treatment protocols for each application.
References
- Dhurat R, Sukesh M. Principles and Methods of Preparation of Platelet-Rich Plasma: A Review and Author’s Perspective. Journal of Cutaneous and Aesthetic Surgery. 2014;7(4):189-197. doi:10.4103/0974-2077.150734.[ncbi]
- Williams, Marlene MD. What are Platelets and Why are They Important?. Heart and Vascular Institute, Johns Hopkins Medicine. Accessed 3.13.2018.[hopkinsmedicine]
- Choi J, Minn KW, Chang H. The Efficacy and Safety of Platelet-Rich Plasma and Adipose-Derived Stem Cells: An Update. Archives of Plastic Surgery. 2012;39(6):585-592. doi:10.5999/aps.2012.39.6.585.[ncbi]
- Dhurat R, Sukesh M. Principles and Methods of Preparation of Platelet-Rich Plasma: A Review and Author’s Perspective. Journal of Cutaneous and Aesthetic Surgery. 2014;7(4):189-197. doi:10.4103/0974-2077.150734.[ncbi]
- Zhang J-M, An J. Cytokines, Inflammation and Pain. International anesthesiology clinics. 2007;45(2):27-37. doi:10.1097/AIA.0b013e318034194e.[ncbi]
- Garraud O, Hamzeh-cognasse H, Cognasse F. Platelets and cytokines: How and why?. Transfus Clin Biol. 2012;19(3):104-8.[ncbi]
- Lubkowska A, Dolegowska B, Banfi G. Growth factor content in PRP and their applicability in medicine. J Biol Regul Homeost Agents. 2012;26(2 Suppl 1):3S-22S.[ncbi]
- Stanford University Medical Center Department of Radiology. Platelet Rich Plasma (PRP) Injection- Information and Instructions for Patients. Accessed 3.13.2018. [stanfordhealthcare]
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